Divergent Effects of Forest Canopy Opening on Soil Fauna and Microbes: A Global Meta-Analysis

Forest canopy opening can significantly affect understory environment and thus further influence the communities of soil biota, but this has not been well quantified in the literature. Here, using meta-analysis method, we evaluated the effects of forest canopy opening on soil fauna density and diversity as well as microbial biomass using 4056 paired observations. We found that (1) as a whole, forest canopy opening showed positive effects on soil fauna communities, significantly increasing the density of total soil fauna by 70.5%, and the total richness, Margalef index, and fungi abundance by 33.1, 30.0, and 64.1%, respectively; (2) canopy opening significantly decreased the Pielou index, bacteria abundance, and soil microbial biomass phosphorus concentration by 16.0, 20.9, and 21.0%, respectively, but did not affect microbial biomass carbon or nitrogen concentration; and (3) forest canopy opening effects on soil biota were regulated by latitude, elevation, climate, canopy opening size, and soil pH, with canopy opening size being the most important factor. Overall, our results demonstrate significantly positive impacts of forest canopy opening on soil fauna and fungi abundance but negative influences on other microbes, which will help us to better understand and predict the responses of soil biota to environmental changes and provide theoretical references for forest management and biodiversity conservation under future environmental change scenarios.